Combining the observations made by JUSTICAR's drones and sensors with the information gleaned from other sources, a picture of the exact nature of this 'island' forms.
There are hidden observation cameras both above and below the waterline, an underwater entrance and even a small submarine attached to a docking port on the bottom of the island.
Inside the island, there is a facility with walls and ceiling lined by some organic growth that must be as hard as enamel to supply the necessary support for it's own weight. A similar organic substance (of differing density) lines the floor.
There is a rudimentary plumbing system, mapping the same allowed some areas to be identified. There appear to be electrical lighting fixtures installed in the ceiling. The ceiling is about ten feet high and the top of the ceiling is just above the waterline.
Airlock - This is a typical setup indicating a room sealed by double doors. One set of doors is at the bottom of the structure, covered in cilia (yes, the swimming tentacles are enlarged cilia). There is a second set of double doors on the west leading into the rest of the facility.
Head - The plumbing attached to these rooms identifies them as bathrooms.
Hatch - These are simple hatches, with a wheel to be opened or closed. There do not appear to be locks on the hatches.